Multi-institutional Comparison Research Articles

Variability of prostate brachytherapy preimplant dosimetry: A multi-institutional analysis

4558 Background: To conduct a multi-institutional comparison of prostate brachytherapy preimplant dosimetry for Pd-103 and I-125. Methods: Eight experienced brachytherapists submitted Pd-103 and I-125 monotherapeutic and boost preimplant dosimetry plans for central review. All 32 plans were calculated using the same transrectal ultrasound volumetric study. Seeds of any strength were acceptable, but were restricted to Theraseed Model 200 (Theragenics, Inc, Buford, GA) and Amersham Oncoseed 6711 (Oncura, Plymouth Meeting, PA). The dosimetric analysis included evaluation of target volume, target to prostate ratio, target length, number of needles, seed activity, number of seeds, total activity, total activity divided by treatment planning volume, the use of extracapsular seeds, and average treatment margins (defined as the perpendicular distance between the prostate capsule and the 100% isodose line). Prostate coverage was defined in terms of V100/150/ 200/300 and D100/90/50 while urethral dosimetry consisted of UV100/150/200 and UD90/50. Results: The mean planning target volume to prostate volume ratio varied dramatically (mean 1.29, range 0.99 - 1.76) with the target length ranging from 3.5 to 4.5 cm. Although the prostate V100 was > 95% in all cases, the V150 ranged from 29.9 to 92.1% and the V200 from 6.72% to 52.5%. The urethra V100 was 100% in all cases with 6 of the 8 brachytherapists limiting the UV150 to < 3%. However, the median urethral dose varied by up to 50%. Treatment margins also varied significantly (average 3.98 mm, range 0.32 - 7.68 mm). All brachytherapists used extracapsular seeds with five implanting > 25% of the seeds in extracapsular locations (range 6.4% - 58.2%). In addition, significant variability existed in the number of needles, the number of seeds, and seed strength. Conclusions: This study highlights that although prostate brachytherapy prescription doses are uniform, substantial variability exists regarding target volume, seed strength, dose homogeneity, treatment margins and extracapsular seed placement. The standardization of preimplant dosimetry is essential for meaningful multi-institutional comparisons of biochemical outcomes and morbidity. No significant financial relationships to disclose.

SU-FF-T-55: Variability of Prostate Brachytherapy Preimplant Dosimetry: A Multi-Institutional Analysis

Purpose: To conduct a multi-institutional comparison of prostate brachytherapy preimplant dosimetry for Pd-103 and I-125. Method and Materials: Eight experienced brachytherapists submitted Pd-103 and I-125 monotherapeutic and boost preimplant dosimetry plans for central review. All 32 plans were calculated using the same transrectal ultrasound volumetric study. Seeds of any strength were acceptable, but were restricted to two manufacturers. The dosimetric analysis included evaluation of target volume, target to prostate ratio, target length, number of needles, seed activity, number of seeds, total activity, total activity per treatment planning volume, use of extracapsular seeds, and average treatment margins (distance between the prostate capsule and the 100% isodose). Prostate coverage was defined in terms of V100/150/ 200/300 and D100/90/50 while urethral dosimetry consisted of UV100/150/200 and UD90/50. Results: The mean planning target volume to prostate volume ratio varied dramatically (mean 1.29, range 0.99 – 1.76) with the target length ranging from 3.5 to 4.5 cm. Although the prostate V100 was > 95% in all cases, the V150 ranged from 29.9 to 92.1% and the V200 from 6.72% to 52.5%. The urethra V100 was 100% in all cases, with 6 of the 8 brachytherapists limiting the UV150 to < 3%. However, the median urethral dose varied by up to 50%. Treatment margins also varied significantly (average 3.98 mm, range 0.32 – 7.68 mm). All brachytherapists used extracapsular seeds with five implanting > 25% of the seeds in extracapsular locations (range 6.4% – 58.2%). In addition, significant variability existed in the number of needles, the number of seeds, and seed strength. Conclusion: This study highlights that although prostate brachytherapy prescription doses are uniform, substantial variability exists regarding target volume, seed strength, dose homogeneity, treatment margins and extracapsular seed placement. The standardization of preimplant dosimetry is essential for meaningful multi-institutional comparisons of biochemical outcomes and morbidity.

Variability of prostate brachytherapy preimplant dosimetry: A multi-institutional analysis

Purpose To conduct a multi-institutional comparison of prostate brachytherapy preimplant dosimetry of Pd-103 and I-125. Methods and materials Eight experienced brachytherapists submitted Pd-103 and I-125 monotherapeutic and boost preimplant dosimetry plans for central review. All 32 plans were calculated using the same transrectal ultrasound volumetric study. Seeds of any strength were acceptable, but were restricted to Theraseed Model 200 (Theragenics Inc., Buford, GA) and Oncura Oncoseed Model 6711 (Oncura, Plymouth Meeting, PA). The dosimetric analysis included evaluation of target volume, target to prostate ratio, target length, number of needles, seed activity, number of seeds, total activity, total activity divided by treatment planning volume, the use of extracapsular seeds, and average treatment margins (defined as the perpendicular distance between the prostate capsule and the 100% isodose line). Prostate coverage was defined in terms of V 100/V 150/V 200/V 300 and D 100/D 90/D 50, whereas urethral dosimetry consisted of UV 100/UV 150/UV 200 and UD 90/UD 50. Results The mean planning target volume to prostate volume ratio varied dramatically (mean 1.29, range 0.99–1.76) with the target length ranging from 3.5 to 4.5 cm. Although the prostate V 100 was >95% in all cases, the V 150 ranged from 29.9% to 92.1% and the V 200 from 6.72% to 52.5%. The urethral V 100 was 100% in all cases with six of the eight brachytherapists limiting the UV 150 to <3%. However, the median urethral dose varied by up to 50%. Treatment margins also varied significantly (average 3.98 mm, range 0.32–7.68 mm). All brachytherapists used extracapsular seeds with five implanting >25% of the seeds in extracapsular locations (range 6.4–58.2%). In addition, significant variability existed in the number of needles, number of seeds, and seed strength. Conclusions This study highlights the substantial variability that exists regarding target volume, seed strength, dose homogeneity, treatment margins, and extracapsular seed placement, although prostate brachytherapy prescription doses are uniform. The standardization of preimplant dosimetry is essential for meaningful multi-institutional comparisons of biochemical outcomes and morbidity.

Impact of Intensivists and ICU Teams on Patient Outcomes

We present a review of the impact of intensivists and ICU teams on patient outcomes, with specific emphasis on varying hospital environments and study designs. While the demand for critical care services is likely to increase, 50% of ICU patients still receive care from nonintensivists in conjunction with consultants. While no “standard” of critical care practice exists, costs are substantial: there are about 55,000 ICU patients/day in the United States, and organizational structures vary substantially. ICU outcome studies can be divided into three groups: multi-institutional comparisons, before-and-after studies, and side-by-side comparisons. Multi-institutional comparisons have tended to show improved outcomes in well-organized ICUs, with strong medical direction and on-site intensivists. The change from an “open” to a “closed” format for ICU care is associated with decreased low-acuity admissions, resource utilization and mortality rates, and improved efficiency. Side-by-side comparisons have demonstrated improved efficiency, decreased complications, and decreased resource use on ICU services directed by an intensivist.

Machiavellianism among Business School Students: A Multi-Institution Comparison

Christie and Geis' Mach IV test was given to 231 senior accounting and management majors at two different universities to assess whether institution attended and specific business major may be associated with Machiavellianism. Scores on Machiavellianism did not vary between accounting and management majors but may be sensitive to the institution which the students choose to attend.